Rcsp new interface overloads

[andreacassioli]

Before submitting

• This PR targets the develop branch.
• I searched for an existing PR or issue covering the same change.
• My contribution is licensed under the Boost Software License 1.0.

Type of change

• Bug fix
• New feature or API addition
• Refactor (no behavior change)
• Documentation
• Build, CI, or tooling
• Other (specify below)

Does this PR introduce a breaking change?

• Yes (describe migration impact below)
• No

What this PR does

• Introduce a new set of interfaces that drop the unused edge index map. The old interfaces are kept but re-wired to the new ones.
• tests are duplicated introducing a dedicated file for the old interface
• examples are duplicated introducing a dedicated file for the old interface
• No logic changes.

Motivation

The current interfaces expose a redundant parameter (edge index map)

• interface cluttering
• less readable code
• less clear behavior (why is that parameter needed?)

The issue has been raised here #342

Testing

Checklist

• Existing tests pass (b2 in the test/ directory).
• New behavior is covered by a test, or this is a docs / build / refactor change.
• Documentation was updated if user-facing behavior changed.
• No new compiler warnings on the platforms I built against.

[github-actions]

Boost dependency footprint vs develop (auto-generated).
PR run 30041728548 vs develop run 29836931414 (7630d5cdf9).

Header-inclusion weights (graph files pulling each direct dependency in):

No header-inclusion-weight changes.

Transitive Boost modules: 68 → 68 (0)

[github-actions]

Compiler-warning counts vs develop (auto-generated).
PR run 30041728537 vs develop run 29836931410 (7630d5cdf9).

Job	Baseline	After	Delta
macos (clang, 14)	4	8	+4
macos (clang, 17)	4	8	+4
macos (clang, 20)	4	8	+4
ubuntu (clang-19, 14)	4	8	+4
ubuntu (clang-19, 17)	4	8	+4
ubuntu (clang-19, 20)	4	8	+4
ubuntu (clang-19, 23)	4	8	+4
ubuntu (gcc-14, 14)	10	17	+7
ubuntu (gcc-14, 17)	10	17	+7
ubuntu (gcc-14, 20)	10	17	+7
ubuntu (gcc-14, 23)	10	17	+7
windows_msvc_14_3 (msvc-14.3)	971	979	+8

[Becheler]

Hi @andreacassioli !

Looks good to me, great work!

To tie it up, we would want to add deprecation notices on the old interfaces as mentioned in the previous conversation so users get a warning (note their position between template args and return type):

#include <boost/config.hpp>

template < class Graph, class VertexIndexMap, class EdgeIndexMap, class Resource_Container, class  Resource_Extension_Function, class Dominance_Function >
BOOST_DEPRECATED("edge_index_map is unused; drop it and call the 5-argument r_c_shortest_paths overload. Removal planned for Boost 1.95.")
void r_c_shortest_paths(const Graph& g, const VertexIndexMap& vertex_index_map, const EdgeIndexMap& edge_index_map, ...)
{
    r_c_shortest_paths(g, vertex_index_map, s, t, ...);
}

Old examples and test files should begin with a #define BOOST_ALLOW_DEPRECATED_SYMBOLS on their first line (before any include) to disable warnings (we know they are outdated and should soon be removed).

See demonstration here: https://godbolt.org/z/dYszsMaea

I think it's reasonable to duplicate the unit tests and the example here (at the cost of blowing up the PR size but there it's a transient inconvenient). If you could quickly confirm locally that the old and new example generate the same output that would be gold! 🙏🏽

Let me know if you have any question,
Thanks again for this cleanup help !
Arno